Manufacture of composite writing points for ball point pens



F. SCHACHT OF R B April 25, 1967 ER 3,315,347 MANUFACTURE COMPOSITE WRITING POINTS 4 F0 ALL POINT PENS Filed Sepf'. 29, 1964 4 Sheets-Sheet l INVENTOR ATTORNEY 4 Sheets-Sheet 2 'INVENTOR ATTORNEY 4 4 3 6 Q a 2 5% 5 5 E s 2 \IUT. H I Hm J .Tww WW m" E T E. a V i Q FRIEDRICH SCHACHTER F. SCHA April 25, 1967 CHTER 3,315,347 SITE WRITING POINTS POINT PENS MANUFACTURE OF COMPO FOR BALL Filed Sept. 29, 1964 April 25, 1967 SCHACHTER 3,315,347

MANUFACTUR F COMPOSITE WRITING POINTS FOR BALL POINT PENS Filed Sept. 29, 1964 4 Sheets-Sheet 5 INVENTOR /jb--'- FRIEDRICH SCHACHTER I 24 BY ATTORNEY United States Patent 3 315,347 MANUFACTURE OF COMPOSITE WRITING POINTS FOR BALL POINT PENS Friedrich Schaciiter, 7333 W. Harrison St, Forest Park, Ill. 60130 Filed Sept. 29, 1964, Ser. No. 400,105 Claims. (Cl. 29-441) This invention relates to new and useful improvements in the art of manufacturing composite writing points for ball point pens.

It is customary in the art to assemble such points from two or more different parts and to fabricate these parts from different materials. For example, it is known to insert into the writing point socket an insert which either consists of very hard material and is already provided with a ball seating surface (as in German Patent No. 827,909), or is made of malleable material into which the ball seating surface is formed by application of pressure to the writing ball after the insert has been placed in the socket (as in United States Patent No. 3,099,082). In either instance, after the writing ball has been inserted in the socket, the front end edge of the socket rim is shrunk around the ball in the usual manner, as for example, by a spinning operation. Furthermore, it is known (as in British Patent No. 665,813), to complete the ball seating surface as well as the lateral surface encircling the ball prior to assembling the respective parts, and to join such parts after an intermediate step of inserting the writing ball.

The simplest and most accurate manner of producing the ball seating surface is by coining, preferably by 1mpression of the writing ball itself. Also, the simplest and most accurate manner of forming a lateral annular gap around the ball is by spinning the rim of the ball socket, such a gap being important in that it determines the thickness and uniformity of the film of ink which is carried :by the ball to the paper. The invention therefore deals primarily with a writing point comprising a ball seating member which supports the ball against writing pressure in an axial direction, and a ball encircling member which forms an annular ink gap around the ball, such members being made from materials having different physical properties.

Conventional writing points of this general type are, for example, assembled from parts which previous to their assembly have been shaped to final form and dimension, with exception of coining the ball seating surface, broaching of ink grooves, and spinning. In such an arrangement the dimensional tolerances of the pre-finished parts accumulate and become further enlarged by tolerances in assembly, so that it is virtually impossible to manufacture writing points with accuracy sufficient to obtain a good writing quality.

It is, therefore, the principal object of the invention to facilitate accurate manufacture of good quality writing points wherein dimensional tolerances of parts may :be kept at minimum and wherein such tolerances do not become cumulative incident to assembly of the parts.

This object is attained by machining the parts to a finish after the parts have first been joined together, such machining being eifected by tool means accurately centered in relation to the parts so that dimensional tolerances may be uniformly held without accumulation, as if the parts were a rigid, unitary entity.

With the foregoing more important object and features in view and such other objects and features as may become apparent as this specification proceeds, the invention will be understood from the following description taken in conjunction with the accompanying drawings, wherein like characters of reference are used to designate like parts, and wherein:

FIGURE 1 is a sectional view, on a large scale, of the ball encircling member per se, prior to assembly and finish machining;

FIGURE 2 is a fragmentary sectional view of the ball seating member per se, also prior to assembly and finish machining;

FIGURE 3 is a sectional view of the parts of FIGS. 1 and 2 assembled;

FIGURE 4 is a sectional view of the assembled parts after the first machining step;

FIGURE 5 is a sectional view thereof after the second machining step;

FIGURE 6 is a sectional view thereof after the third machining step;

FIGURE 7 is a sectional view of the assembled and finish machined parts with the ball in place and the ball seating surface coined by application of pressure to the ball;

FIGURE 8 is a sectional view of the assembled writing point with the ball encircling member spun around the ball;

FIGURE 9 is an enlarged, fragmentary sectional detail of the completed writing point;

FIGURE 10 is an elevational view of material stock in spherical form, for use in making the ball encircling member of FIGURES 1114;

FIGURE 11 is a sectional view showing the material stock of FIG. 10 subiected to a cold heading operation to form the ball encircling member;

FIGURE 12 is a sectional view of the ball encircling member of FIG. 11 assembled to a ball seating member;

FIGURE 13 is a sectional view of the assembled parts of FIG. 12 after a first machining step;

FIGURE 14 is a sectional view of the parts after a second machining step;

FIGURE 15A'is a fragmentary sectional view of assembled ball encircling and seating members in a modified embodiment prior to machining;

FIGURE 15B is a fragmentary sectional view of the parts of FIG. 15A in a machined condition and with a separate ball seat in place;

FIGURE 16A is a fragmentary sectional view of assembled parts in another modified embodiment prior to machining;

FIGURE 16B is a fragmentary sectional view of the assembled parts of FIG. 16A in a machined condition and with the ball in place;

FIGURE 17 is a fragmentary sectional view showing assembled parts of another modified embodiment in an intermediate stage of manufacture; and

FIGURE 18 is a fragmentary sectional view of still another modified embodiment in an intermediate manufacturing stage.

Refering now to the accompanying drawings in detail, more particularly to FIGS. 1-9, for purposes of general orientation reference is first drawn to FIGS. 8 and 9 which show the assembled, finish machined and otherwise completed writing point of a ball point pen. As such, the writing point comprises what may be generally designated as a ball seating member 20, a writing ball 21, and a ball encircling member 22. The ball seating member 20 is in the form of a diametrically reduced neck 23 provided at one end of a cylindrical point body 24, an annular shoulder 25 existing around the base of the neck for abutment with the base edge 26 of the ball encircling member 22 when the latter is pressed into position on the neck 23, as shown.

FIGS. 1 and 2 show the members 22, 20, respectively, prior to their assembly, both members being suitably pre-formed, as by a screw machine, for example, with the end of the neck 23 being chamfered as at 27 to facilitate its subsequent insertion into the member 22, and the member 22 having an initial axial bore 28 with a bevelled end 29 to facilitate its passage over the neck 23 during assembly. The body 24 of the member is also preformed with a blind axial bore or chamber which constitutes or communicates with the ink reservoir of the pen, it being noted that as pre-formed, the ink chamber 30 terminates short of the neck 23, rearwardly of the shoulder 25.

The members 20 and 22 are made of different materials, the material of the ball encircling member 22 preferably being harder than that of the ball seating member 20. Thus, the member 22 may be made of stainless steel with Brinell hardness of 220, for example, while the member 20 may be made of free-machining brass with Brinell hardness of 130, for example.

The inside diameter of the member 22, that is, the diameter of the bore 28, fits the outside diameter of the neck 23 within very close limits, so that the two parts may be press-fitted together. The shoulder 25 is square to the axis of the neck 23, the base edge 26 is square to the axis of the member 22, and the outside conical surface 31 of the member 22 is concentric with the bore 28. The forward end edge 32 of the member 22 is not finished at the pre-formed stage of the member.

With the parts 20, 22 pre-formed as described, the first step is to assemble the same as shown in FIG. 3, which may be done by holding the member 20 relatively stationary and press-fitting the member 22 on the neck 23, as by a pressing tool 33 having a frusto-conical socket 34 for reception of the member 22. When so assembled, the two parts 20, 22 are rigidly united.

In the next operational step shown in FIG. 4, the assembled parts 20, 22 are firmly held, as in a fixture 35 having a tapered socket 36 which accurately fits the outer surface 31 of the member 22. A complemental fixture 37 is accurately seated on and axially aligned with the fixture 35, the fixture 37 providing an accurate guide for a drilling tool, such as a spade drill 38 which is axially movable in the fixture 37 and may be advanced to form a center 39 in the neck 23, without touching the member 22.

With the assembled parts in the fixture 35a, the next operational step is undertaken as in FIG. 5, wherein a drilling tool such as a twist drill 40, concentrically guided by the fixture 37a, is advanced into the center 39 to form a central duct 41 which breaks through into the ink chamber 30, as shown. The drill is preferably of a smaller diameter than the drill 38.

In the next operational step shown in FIG. 6, the assembled parts are held in the fixture 35b and a boring tool 43 is used to finish machine the parts. The tool 43 is carried by a spindle 44 concentrically guided by the fixture 37b, the tool having a conical point 45, a cylindrical portion 46, a frusto-conical portion 47, a further cylindrical portion 48, and an annular face 49.

When the tool 43 is advanced into the work, the conical point 45 and the cylindrical tool portion 46 cuts into the center 39 producing the surfaces 42 and 42a; the cylindrical tool portion 48 cuts into the bore 28 of the member 22 to produce a finished side wall surface the frusto-conical tool portion 47 cuts into both the member 22 and the neck 23 so as to completely remove the chamfer 27 of the neck and to form in the neck a frusto-conica-l ball seating surface 51 which diverges beyond the outside diameter of the neck into the member 22 to meet the finished side wall surface 50 of that member; and as advancement of the tool continues, the tool face 49 finishes off the outer end edge 32 of the member 22 as at 32'. The machining operation of the tool 43 will be evident from FIG. 6, it being noted that inasmuch as the already assembled parts 20, 22 are firmly held in the fixture 35b in proper concentric relation with the tool 43 guided by the cooperating fixture 37b, the surfaces 50 and 51 may be machined 'with a high degree of accuracy, t-rue concentricity and minimum tolerance, as if the parts 20, 22 were integrally formed.

After the usual ink grooves 52 are broached or otherwise formed in a conventional manner, the next operational step involves the insertion of the writing ball 21 into the ball encircling member 22 so that the ball engages the seating surface 51 of the member 20, as shown in FIG. 7. Axial pressure is then applied to the ball 21 as at 53, so that the seating surface is impressionally coined to the exact curvature of the ball, as is clearly shown at 51' in the enlarged view of the finished product in FIG. 9.

In FIG. 8 conventional spinning tool means 54 are shown as being applied to the outer or front edge portion or rim of the ball encircling member 22 so as to shrink the same around the ball 21 as at 55, with an annular ink gap 56 existing between the ball and the finished side wall 50 of the member 22, as in FIG. 9.

By cold working the material of the member 22 in the spinning of the rim portion 55, the wear resistance of the material is increased so that the member 22 and particularly the rim portion 55 thereof may withstand abrasive action of paper minerals, debris, et cetera.

It may be noted that the finish machining operation by the boring tool 43 is a chip removing operation in which chips of material are removed from the work to produce the finished surfaces 50, 51. By using the tool 43, both these surfaces may be machined at the same time, or if preferred, separate tools may be employed to machine the respective surfaces successively. Also, while the ball seating surface 51' is preferably coined impressionally by the writing ball 21 itself, a pressure member with a convex surface (not shown) corresponding to the writing ball may be used for coining the surface 51'.

Referring now to FIGS. 10-14, inclusive, these show a somewhat modified arrangement wherein the ball encircling rnember 61) is pre-formed by a cold heading operation. The member 60 is made of stainless steel, for example, in wire form which is cut into short cylindrical slugs, the slugs being rounded to produce balls, one of which is shown in FIG. 10. The ball 60' preferably is hardened, then ground to a precise spherical form, and then is annealed, the grain structure of the ball being carefully controlled during these operations.

As shown in FIG. 11, the ball 60' is then applied to a die 61 having a cavity 62 corresponding to the outside configuration of the member 60 which is to be formed, while a cooperating punch 63, of a configuration corresponding to the inside of the member 60, is brought into the die so that the ball 60 is transformed by cold heading into the member 60. The punch 63 is slidably positioned in a guide 64, cooperating with the die 61.

The ball encircling member 60 so pre-formed is then pressed on the neck 23 of the ball seating member 21 as in FIG. 12, this being carried out as already described in connection with FIG. 3.

Unlike the member 22, the member 60 has a closed outer end, indicated at 60" in FIGS. 11 and 12, and in the next operational step shown in FIG. 13 the member 60 is accurately held in the fixture 35 and the spade drill 38, guided by the fixture 37, is used to drill through the closed end of the member as at 65 and also to form the center 39 in the neck 23. A twist drill 40 is then used in the fixture 37a to form the ink duct 41 as in FIG. 14. The ball encircling surface 50 and the ball seating surface 51 are then finish machined in the parts 60, 23, respectively, as described in connection with FIG. 6, whereupon the ball seating surface is coined by the inserted writing ball and the encircling member 60 is spun around the ball, as before.

If desired, the member 60 may be annealed after the cold heading operation so as to make it more readily machinable by the chip removing process. By making the member 60 from the initial ball 60', the diameter and volume of the ball may be accurately held so as to completely fill the die 61 when the punch-63 is inserted, without any excess material being left at the end of the cold heading operation. Thus, formation of flash is eliminated on the formed part at the parting lines of the punch and die. Also the grain structure of the part 60 may be accurately controlled, so that the part may respond uniformly to the various subsequent operational procedures. Incidentially it may be observed that while in FIGS. 1-9 the outside of the neck 23 and the inside of the member 22 are straight, in FIGS. -14 the same preferably are tapered so as to facilitate withdrawal of the cold headed member 60 from the forming die 61.

Referring now to FIGS. A and 15B, another modified arrangement is shown wherein the writing point comprises a ball seating member 20, a ball 21 and 'a ball encircling member 22, but a separate seat 68 is used for the actual seating of the ball. After the preformed parts and 22 have been assembled as in FIG. 15A and the surfaces 50 and 51 finish machined, as previously described, after which the seat 68 is inserted and the ball 21 applied thereto under pressure to coin the ball seating surface 69. The seat 68 is formed from a wire ring and is deformed during application of the ball pressure thereto, as for example, in my United States Patent No. 2,969,583, dated Jan. 31, 1961.

In another modified embodiment shown in FIGS. 16A and 16B, a tubular ball encircling member 70 is pressed on the neck 23 of the ball seating member 20 and a circular disc 71 is pressed into the member 70 so that it abuts the end of the neck 23. Thereupon the outer conical surface 31 of the member 70 is produced and the ball encircling and seating surfaces 50, 51, respectively, are finish machined as previously described, the ball seating surface 51 in this instance being formed in the disc 71 rather than in the neck 23 itself.

The further modified embodiments shown in FIGS. 17 and 18 employ a ball encircling portion or member 74 which is integral with the point body 75, being formed from stainless steel, for example, and containing an insert 76 which is press-fitted into the cavity 77 of the member 74. After the parts are assembled, the surfaces 50, 51 are finish machined concentrically with the outer surface 31 as previously described, the ink grooves 52 are formed, and the ball 21 is inserted. Thereupon the ball seating surface is impressionally coined on the surface 51 and the rim of the portion 74 is spun around the ball. While in FIG. 17 the usual ink grooves 52 are provided, in FIG. 18 the ink grooves 78 are formed on the outer rather than the inner surface of the insert 76.

A word may be added concerning the characteristics of materials used in making the parts which provide the ball encircling and ball seating surfaces. Deterioration of writing quality of a ball point pen is primarily caused by wear of the ball encircling surface which undergoes erosion by the lapping action of paper minerals and debris carried by the ink film from the paper back into the ball socket. The wear of the ball seating surface and the therewith associated axial displacement of the ball plays a relatively minor role in deterioration of writing quality, inasmuch as debris carried into the ball socket by the ink film is scraped from the ball by the outer edge of the ball seating surface so that very little of such debris reaches the seating surface itself, particularly since the ball is firmly pressed against the seating surface by writing pressure. On the other hand, the annular ink gap existing between the ball and the ball encircling surface is of such size that debris is carried by the ink film into the gap and causes the ball encircling surface to erode, thus creating an enlargement of the annular gap and impairing the ink metering action so that the writing quality is markedly affected. It thus follows that the ball encircling member which provides the ball encircling surface should be made of material which has a high resistance to wear and erosion by debris, while the ball seating member may 6 be of relatively softer material which lends itself well to machining by chip removal and coining.

Good wear resistant materials suitable for making the ball encircling member are steel alloys, Monel, alloys of precious metals, bronzes, sintered metals, syntheticmaterials, and the like. Stainless steel of the following composition has been found to be especially suitable: C 0.1; Mn 0.4; Si 0.5; P 0.01; S 0.35; Cr 13; Mi 0.3; M0 0.05; Cu 0.1.

Due to its high sulphur content, this alloy may be easily machined by chip removal to obtain surfaces of high quality and accuracy. Also, it shows an advantageous behavior during the spinning operation whereby the hardness of the curved surface engaging the ball increases to more than double the value of the initial hardness.

For the part which provides the ball seating surface, free machining brass may be used, with a lead content of 3%, or so called fine grain silver, with an addition of 0.5% Ni as well as other materials such as tin.

The point body 24 with the neck 23 as shown in FIGS. 15A, 15B, 16A and 16B may be made from synthetic materials, integrally with the ink reservoir of the pen, if so desired.

While in the foregoing there have been described and shown the preferred embodiments of the invention, various modifications may bcome apparent to those skilled in the art to which the invention relates. Accordingly, it is not desired to limit the invention to this disclosure, and various modifications and equivalents may be resorted to, falling within the spirit and scope of the invention as claimed.

What is claimed as new is:

1. A method of making a writng point for a ball point pen or the like, wherein the point includes initially separate concentric annular ball encircling and ball seating members and wherein the seating member is finally shaped by the application under pressure to the ball seating member of a pressure member having a rounded convex surface corresponding to the shape of the pen ball, and subsequently creating an annular ink well gap by spinning the ball encircling member about the pen ball; the improvement comprising assembling and securely fitting the ball seating member within the ball encircling member and thereafter machining the ball seating member with tool means centered upon the ball encircling member to remove a portion of the material from the ball seating member prior to finishing the seat by the application of said rounded pressure member.

2. A method of making writing points for ball point pens or the like, wherein the point includes initially separate concentric annular ball encircling and ball seating members, the ball encircling member being of relatively hard material and the ball seating member being of a softer malleable material, which method comprises assembling and securely fitting the ball seating member within the ball encircling member, then machining both parts with tool means which operates on both members concentrically to at least partially shape the ball encircling member and the ball seating member, then completing the formation of the ball seating member by applying a rounded member having the shape of the pen ball to the seat, and then spinning the ball encircling member about the pen ball.

3. In a method of making a writing point pen or the like, wherein the point includes initially separate ball encircling and ball seating members; the steps of first assembling the ball encircling and ball seating members into a rigid entity, and thereafter machining the assembled members with tool means centered upon the ball encircling member to at least partially shape said assembled members and then providing encircling and seating surfaces for a pen ball.

4. In a method of making a writing point for a ball point pen or the like, wherein the point includes initially separate ball encircling and ball seating members adapted point for a ball to ultimately provide encircling and seating surf-aces respectively for a pen ball; the steps of first assembling the ball encircling and ball seating members into a rigid entity, centering machine tool means concentrically on the outer surface of the ball encircling member, and then machining the assembled members to form a ball encircling surface in the encircling member and a ball seating surface on the seating member by said tool means.

5. The method as defined in claim 4 together with the step of finishing the ball seating surface of said seating member by application thereto of a pressure exerting member corresponding to the contour of a pen ball.

6. In a method of making a writing point for a ball point pen or the like, wherein the point includes a ball encircling member of relatively hard material and a ball seating member of softer malleable material which is initially separate from the ball encircling member; the steps of first assembling the ball encircling and seating members into a rigid entity, centering machine tool means concentrically on the outer surface of the ball encircling member, machining the assembled members by said tool means to form a ball encircling surface in the encircling member and a ball seating surface in the seating member, inserting a writing ball into the ball encircling member so as to engage said ball seating surface, applying pressure to said ball so as to coin an impression thereof in said seating surface, and then spinning the ball encircling member about said ball.

7. The method of making a writing point for a ball pen as defined in claim 1 wherein the ball encircling member is initially formed by the steps of rounding stock material into a spherical form, placing the spherical stock in a die with a cavity corresponding to the outside configuration of a ball encircling member to be formed, and advancing into the die a punch corresponding to the inside configuration of the member to be formed, with the material volume of the formed member being precisely equal to the volume of the spherical stock.

8. In a method of making a writing point for a ball point pen or the like, wherein the point includes a ball encircling member, a ball seating member, a ball and a ball seat all initially separate from one another; the steps of first assembling the ball encircling member and the ball seating member into a rigid entity, then machining the assembled members with tool means centered upon the ball encircling member to provide a ball encircling surface in the encircling member and a ball seating surface on the seating member, tightly fitting the ball seat into the ball encircling member against the seating surface of the seating member, placing the ball against the ball seat, and applying pressure to the ball so as to coin an impression thereof in said seat.

9. In a method of making a writing point for a ball point pen or the like, wherein the point includes a ball encircling member, a ball seating member, a ball and a ball seat all initially separate from one another; the steps of first assembling the ball encircling member and the ball seating member and the ball seat into a rigid entity, then machining the assembled members and seat to provide a ball encircling surface in the encircling member and a ball seating surface on said seat, placing the ball against the seat, and applying pressure to the ball so as to coin an impression thereof in said seating surface.

10. In a method of making a writing point for a ball point pen or the like, wherein the point includes a ball encircling member and an initially separate ball seat member; the steps of first inserting the ball seat member into said encircling member to form a rigid assembled entity, and then machining the assembled member and seat member with tool means centered upon the ball encircling member to at least partially shape said assembled members and then providing a ball encircling surface in said member and a ball seating surface on said seat member.

References Cited by the Examiner UNITED STATES PATENTS 2,718,051 9/1955 Cloutier 29-441 2,969,583 1/ 1961 Schachter 29-441 3,036,367 5/1962 Ricks 29-441 3,099,082 7/ 1963 Henriksen 29-441 3,181,228 5/1965 Droubay 29149.5

FOREIGN PATENTS 148,030 9/ 1952 Australia.

JOHN F. CAMPBELL, Primary Examiner. THOMAS H. EAGER, Examiner. 

1. A METHOD OF MAKING A WRITING POINT FOR A BALL POINT PEN OR THE LIKE, WHEREIN THE POINT INCLUDES INITIALLY SEPARATE CONCENTRIC ANNULAR BALL ENCIRLING AND BALL SEATING MEMBERS AND WHEREIN THE SEATING MEMBER IS FINALLY SHAPED BY THE APPLICATION UNDER PRESSURE TO THE BALL SEATING MEMBER OF A PRESSURE MEMBER HAVING A ROUNDED CONVEX SURFACE CORRESPONDING TO THE SHAPE OF THE PEN BALL, AND SUBSEQUENTLY CREATING AN ANNULAR INK WELL GAP BY SPINNING THE BALL ENCIRCLING MEMBER ABOUT THE PEN BALL; THE IMPROVEMENT COMPRISING ASSEMBLING AND SECURELY FITTING THE 